Detector for electromagnetic waves or the like.



N'Or 820,258 PATENTED MAY 8, 1906.

I R. H. RENDAHL.

DETECTOR FOR ELECTROMAGNETIC WAVES OR THE LIKE.

APPLIOATION FILED APR. 18,1905.

RAGNAR H. RENDAHL, or BERLIN,

SCHA Fl MANY.

(JrERMANY,v ASSIGNOR TO GESELL- FUR DRAHTLOSE TELEGRAPHIE M. B. H., OF BERLIN, GER- DETECTOR FOR ELECTROMAGNETIC WAVES on THE LIKE.

Specification of Letters Patent.

Patented May a, 1906.

Application iiled April 18, 1905- Sarial No. 256,290.

To all whom it mag concern:

Be it known that I, RAGNAR HAKaN REN DAHL, en ineer, a subject of the King of Sweden and orway, residin at 13 Hollmannstrasse, Berlin, S. W., erman ,have invented certain new and useful Improvevments in Detectorsv for Electromagnetic Waves or the Like, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

This invention relates to a detectorforelectromagnetic waves or other Weak impulses, which detector consists, substantially, of an 15 electrolytic cell of-a well-known type with a minute anode.v In articular it relates to those detectors in w ich the electrolytic cell is combined with means for polarizing the cell and means for passing the waves or, impulses through the cell, thereby causing a partial or complete depolarization of the cell. This partial or complete depolarization of the cel causes a' strengthening of the current flowing through it, which may be ascertained by suitable means'for instance, by means of a telephone. Now experiments have shown hat several detectors of this kind. in spite of their-external or construe tional simllarity difl'er considerably one from another in their electrical behavior. If the action of the cells under the influence of electric waves be observed by means of a telephone in some of the cells, which as compared with one another areexternally or con 3 5 structionally completely similar, a maximum volume of sound in the telephone is attained with a definitely-determined wave len' th of the impulse acting on the cells, while in other cells the strength of the sound remains constant with any wave-length. Some cells even alter their action as regards this point. Experiments which were -m'ade to investigate this behavior brought me to the opin- 4 1011 that the electrolytic cell does not directly transmit the entire strength of current flowing through it, but rather in its action must -be considered as a pure papacity, (condenser capacity,) an electrolytic capacit (capacity of polarization) serving as root er, and an ohmic resistance, all connected in arallel, and that the mutual proportion these threeelectric quantities does not remain necessafily constant, owing to the. ex-

sistance-and consists in connecting etween OGlVGT-StiLtIODS for wire shown diagrammatically.

ternal or constructionalsimilarity of the cells so far as this is attainable by manufacture. The percentage of consumption of energy of the cells per oscillation-that is to say, the lproportion of the energy consumed per oscil ation and the. total amount of energy of the oscillation conveyed to the celldepends now on this mutual ratio of the three electric quantities; in fact, it is smaller the greater the-electrolytic capacity of the cell.

If the wave-detector be considered in combination with a receiver for space telegraphy, the cell must have a certain ercentage of consum tion of energy per oscillation in order to best utilize an oscillation of given damping, which is to be received-'that is to say, to make it more readily distinguishable in the telephoneand the percentage of consumption of energy of the cell per oscillation must, onthe other hand, be made as small as possible-that is to say, the electrolytic capacity of the cell kept as large as possible in order to produce very shar tuning, avoiding the maximum intensity. 11 order, therefore, first, on receipt of waves with difierent damping to obtain the greatest intensity, second, to be able to'suita ly increase the sharpness of. the tuning, and, third, to be unafi'ected by unavoidable inequalities in the manufacture, itis necessary to be able to regulate or correct the ercentage of consumption of energy of the cel pro ortion between the pure capacity action an the roperties of the cell-consuming energy bye ectric rectifier and ohmic resistance.

Various experiments have been made to 0btain this by a variation of the su erficial areas of the electrodesfor instance, y varying the amount immersed. These methods,

however, do not allow of the alteration of the quantity only, butinvolve the simultaneous alterationof all the said electrical quantities-oi the cell. Now this invention afiords a means of varying-the non-energy- -consuming property of the -cell-that is to say the me condenser action independently of t e energy-consuming pro ertiesnamely, electrolytic capacity and o mic reana'dj ustable condenser in parallel with the cell.

' the accompanying drawings two reess telegraphy are lper osc1llationthat is to say, the

impulses.

Figure 1 shows a receiver in which the electrolytic cell a is directly inserted in the aerial conductor. The source of current b is connected with the electrodes of the cell by means of choking-coils c, in the 'circuit of which source of current a telephone d is inserted. The adjustable condenser f lies in parallel with the electrolytic cell.

' In the receiver shown in Fig. 2 the electrolytic cell it lies in a separate detector-circuit containing the condenser g and the secondary coil h of a transformer. The primary coil i of the transformer is inserted in the receivercircuit. The battery I) is connected through choking-coils c to the cell, and in arallel with this a condenser f is inserted. n the latter case the maximum receiver intensity for the given damping of the transmitter and receiver necessitates not only a certain adjustment of the condenser inserted in arallel to the cell, but also a certain degree 0 the coupling between the receiver and the indicator circuitthat is to' say, a certain speed of the traveling of energy from the receiver-circuit to the detector-circuit.

1 It follows without further explanation from what has been hereinbefore stated that the sizes of the most favorable condenser parallel to the cell may serve as a scale for the damping of the transmitter.

Having explained my invention, what I claim, and desire to secure by Letters Patent, is

'1. In apparatus ofthe character described, the combination with an electrolytic detector, of means for varying or adjusting the nonenergy-consuming propert .or factor of said detector independently o the energy-consuming properties thereof.

2. In a detector of electromagnetic waves or other feeble electrical im ulses, the combination of an electrolytic ce 1, means for polarizing such cell, a condenser parallel to said cell, means for Ipassing the waves or impulses and means for observing increases n current caused by said waves or 3: In a detector of electromagnetic waves or other feeble electrical impulses, the combination of an electrolytic cell having a minute anode and a cathode of greater surface, means for polarizing such cell, a condenser parallel tosaid cell, means for passing the waves or impulses through the cell and means for observing increases in current caused by said'waves or impulses.

4. In a detector of electromagnetic waves or other feeble electrical impulses, the combination of an electrolytic cell, a'source of electromotive force for polarizing such cell and producing at the cell a voltage above the decom osition voltage of the cell, a condenser paralle to said cell, means for passing the waves or impulses through the cell and means for observing increases in current caused by the cell by the influence of said wavesor impulses.

I 5. In a detector of electromagnetic waves or other feeble electrical impulses, the combination of an electrolytic cell having a minute anode, a local circuit connected across the cell and including a source of direct electroinotive force having its positive pole connected with the minute anode and acting to polarize the cell, a condenser parallel to said cell, means for assing the waves or impulses through the cell and means for observing increases in current caused by a depolarization of the cell by the influence of said waves or impulses.

' 6. In a receiver for space tele raphy the combination of an electrolytic ce 1 conduct- ;ively connected with the receiving-circuit, a local circuit connected across the cell and including a source of direct electromotive force for polarizing such cell and producing at the cell a voltage above the decomposition voltage of the cell, a condenser of a variable capacity parallel to the cell and means for observing increases in current caused by a depolarization of the cell by the influence of the Waves produced in the receivingcircuit 7. In a receiver for space telegraphy the combination of an oscillating circuit includi'ng a self-induction, a condenser and an electrolytic cell in series and inductively connect- 5 ed with the receiving-circuit, a source of electromotive force for polarizingthe said cell and producing at the cell a voltage above the decomposition voltage of the cell, a condenser of a variable capacity parallel to the cell and means for observing increases in current caused" bya depolarization of the cell by the influence of the waves produced in the said oscillating circuit.

In witness whereof I hereunto subscribe my name this 3d day of April, A. D. 1905.

RAGNAR H. RENDAHL.

Witnesses WOLDEMAR HAUPT,

HENRY HASPER. 

